Spark plug



Aug. 30, 1938. A. M. FAIRCHILD S PARK PLUG Filed Dec. 14, 1956 WWWWI Z INVENTOR. 671608 BY ATTORNEY.

Patented Aug. 30, 1938 PATENT OFFICE SPARK PLUG Alice M. Falrchild, Chicago, 111., asslgnor sears,- .Roebuck and 00., Chicago, Ill., a corporation of New York Application December 14, 1936, Serial No. 115,707

7 Claims.

My invention relates to spark plugs for use in internal combustion engines.

It is not uncommon for spark plugs of the usual type to become fouled with carbon, especially 6 when a poor grade of motor fuel is employed, or when the carburetor is improperly adjusted, etc. Such fouling results in short circuiting of the spark plug, thus reducing the power of the motor.

In Harding Patent No. 1,275,020, patented Au- W gust 6, 1918, there is disclosed a spark plug containing a ceramic catalyst which is said to function to produce flameless catalytic combustion of part of the explosive vapor and thus keep the parts, especially the insulator, free from deposits 15 of carbon.

An object of my invention is to provide an improved spark plug having a catalyst which will function to prevent the deposition of carbon and consequent short circuiting of the plug.

A further object is to devise such a device which will utilize a substantially standard form of spark plug, modified only slightly and at very little ex pense, in order to accomplish the objects of my invention.

25 In accordance with a preferred embodiment 01 my invention, in a spark plug comprising a core portion and a shell portion, I provide a continuous zone of catalytic material on the surface of the insulator and spaced from the electrodes or 30 sparking points and integral with the insulator, so that said points can neverbe short circuited. This zone is in the porcelain core and may be formed in various ways, as described in more detail below.

35 Referring now to the drawing forming a part of this specification and illustrating a preferred embodiment of my invention,

Fig. 1 is a plan view of the core element of a spark plug embodying my invention,

40 Fig. 2 is a similar view of a complete spark plug embodying my invention, parts of the same being shown in longitudinal section,

Fig. 3 is a transverse half section takensubstantially long the line 3-3 of Fig. 1, and

-i5 Fig. 4 is a fragmentary sectional view taken substantially along the line 4-4 of Fig. 3. v

Although I have illustrated my invention as applied to a particular design of spark plug, it will be understood that said invention is applicable 50 to various other designs and constructions.

In the embodiment shown, there is a. substantially cylindrical shell portion I which is externally screw threaded as at l2 for threaded engagement in a cylinder of an internal combustion 55 engine. Said shell portion is usually formed of a (Cl. 123-169) i metal which is a good electrical conductor, thus serving to ground the parts electrically when screwed into the cylinder. .Seated in the end oi the shell I is an electrode or sparking point l3.

Seated within the shell I0 is a core element or 5 insulator I 5 which may be formed of porcelain or other suitable insulating material. Said element may be retained in shell ID by means of a nut or bushing Hi, the latter being threaded into the shell as at IT, and suitable expansion rings being I provided as at I8, I8. An electrode 20 is seated in the core element l5 and arranged axially thereof, said electrode 20 being electrically connected to a terminal 2|, whereby an electrical conductor from a source of electricity may be attached.

The core element I5 is tapered adjacent the exposed or sparking end of electrode to provide a substantially frusto-conical portion 25, defining a channel 24 between the core and shell. It will 2 be apparent that this portion of the insulator may have other shapes. On the outer surface of portion 25 of the insulatorI provide an annular zone 26 of catalytic material capable, when heated, of producing flameless catalytic combustion of a 25 portion of the combustible vapor introduced into the cylinder.

The catalytic material to which I refer belongs to a. class which is well known and is described in Harding Patents 1,275,020, dated August 6, 1918; 30 803,534, dated October 31, 1905, and 1,067,983, dated July 22, 1913. Said catalytic structures are composed principally of the rare earth metals, such as thorium, uranium, etc., or oxides thereof, together with a member or members of the platinum group. The preparation of such catalytic material is well known to those skilled in the art.

In the manufacture of spark plugs embodying my invention, it is my object, as stated above, to apply a continuous zone of catalytic material 49 without deviating substantially from standard plug design. I accordingly apply said catalytic material in the form of a solution of the chloride or nitrate of the desired elements to the plug, as by painting or otherwise applying the same, preferably on the frusto-conical stud portion 25 of the core l5, as indicated at 26.

I have found that the catalytic solution adheres best to the core and makes a firmer bond therewith if the surface of the care is abraded 50 so as to provide a more or less toothed surface.

It appears that the solution penetrates into the ceramic material to a slight extent, said solution carrying the catalytic salts which thus impregnate the ceramic body. However, whether or not there is any actual penetration is immaterial, the important point being merely that the catalytic material does obtain an improved footing by reason of the roughing or grinding of the surface. In the embodiment shown, the stud portion 25 is ground away to a slight extent to provide an annular groove of slight depth and the catalytic solution is applied to said groove as shown at 2'. After the catalytic solution has annular zone of catalytic material for preventing deposition of carbon, said zone being spaced a substantial distance from the electrode end of said insulator.

2. A spark plug insulator havinga stud portion with an electrode projecting therefrom, said portion being provided with a continuous peripheral roughened area and said area being impregnated with rare earth cataLvtic substances capabeen applied as described above, the material is ble of preventing the deposition of carbon.

hydrated by exposure to NH: gas, the liquid 3. A spark plug insulator having a stud poris evaporated of! and the article is then fired tion with an electrode projectingtherefrom, said at a relatively high temperature, say about 2600 portion being provided with an annular groove degrees F., in order to convert the salts into the bearing catalytic substances capable of preventmetallic state, and the article is then ready for ing deposition of carbon, said groove being spaced use. a substantial distance from both ends of said The action of my improved spark plug is as stud portion. follows: When a charge of fuel is introduced 4. The method of producing an article of the into the cylinder 9. portion thereof enters the class described, comprising abrading the surface space, between the stud portion of the core ii of a spark plug insulator to provide an annular and the shell ID. A portion of said fuel may be zone thereon, and applying to said zone a catacompounds of relatively high molecular weight lytic substance in the form of a solution whereby which are not completely combustible under the said insulator becomes impregnated with said normal temperatures and other operating consubstance.

25 ditions present in the cylinder, and, being slow 5. A spark plug insulator having a catalytic moving due to the dead end of said space, norzone of radio-active elements integral with said mally tend to deposit carbon therein, which insulator and spaced a substantial distance from would eventually short circuit the spark plug. the electrode end therof, said zone serving to The catalytic zone 26 tends to produce flameless scavenge the slow moving gases by breaking up 30 catalytic combustion within the channel 24, thus and eliminating from the surface of said insuscavenging said products out of said space. At lator by catalysis the carbon forming unburned any rate, itis found that plugs embodying my gaseous compounds. invention do not become fouled with carbon and 6. A spark plug insulator having a stud porthus have a much longer eflective life than ordition with an electrode projecting therefrom, said nary spark plugs. portion being provided with a continuous periph- I may apply the coating 28 of catalytic mateera] roughened area and said area being impregrial in one or several coats or applications. In nated with rare earth catalytic substances capasome cases, I iind that the material makes a ble of preventing the deposition of carbon, said firmer bond with the ceramic material when a area being spaced a substantial distance from the base coat is applied and dried and another coat electrode end of the insulator.

then applied.

Various other changes coming within the spirit of my invention may suggest themselves to those skilled in the art and hence I do not wish to be r limited to the specific forms shown or uses mentioned, except to the extent indicated in the appended claims, which are to be interpreted as broadly as the state of the art will permit.

I claim:

l. A spark plug insulator having an integral 7. A spark plug insulator having a catalytic zone of radio-active elements impregnating a continuous peripheral roughened area spaced a substantial distance from the electrode end of said insulator, said zone serving a scavenge the slow moving gases by breaking up and eliminating from the surface of said insulator by catalysis the carbon forming unburned gaseous compounds.

ALICE M. FAIRCHILD.

CERTIFICATE OF- CORRECTION.

Patent No. 2,128,157. August 50, 1958.

ALICE li. FAIRCHILD.

It is hereby certified that error appears -in the printed specification of the above numbered patent requiring correction as follows: Page 1 first column, line 1 1;, for -"long" read along; and second column, line 50, for "care" read core; page 2, second column, line 15, claim 7, for the article "a' read to; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent: Office.

Signed and sealed this 11th day of October, A. D. 1938..

Henry Van Arsdale (Seal) Acting Commissioner of Patents. 

